1. Field of the Invention
The present invention relates to a reaction cartridge to be used for conducting a biochemical reaction that has a reaction chamber in which a probe carrier is arranged to carry a detection probe immobilized to a substrate. More particularly, the present invention relates to a reaction cartridge to be used for conducting a biochemical reaction by using a specimen solution containing molecules of a living body that interact with a detection probe, washing liquid, air, etc., a reaction apparatus to be used for biochemical reactions and a method of moving solution in a reaction cartridge.
2. Description of the Related Art
A hybridization method is used to identify the partial sequence included in the base sequence of a nucleic acid molecule or detect the living body or bodies such as microbes contained in a specimen. With a hybridization method, it is determined whether or not a molecule of the target nucleic acid contained in a specimen specifically binds to the probe DNA whose base sequence is known in advance. Techniques are known for utilizing a probe array (also referred to as micro-array) that is formed by regularly arranging regions (probe spots) where probe DNAs of a plurality of different types are respectively immobilized on a substrate for the purpose of conducting a hybridization method accurately and effectively. With such a technique, it is possible to carry out detecting operations concurrently for a plurality of items because it is possible to determine whether molecules in the specimen bind to the probe DNAs of a plurality of different types. With a hybridization method using such a micro-array, bio-polymers in a solution are subjected to hybridization with the probes arranged regularly on a substrate for analysis such as detection and quantification of a target nucleic acid. For a hybridization reaction, hybridization solution is filled into a reaction chamber comprising as a component a a substrate where probes are immobilized and the substrate is held at a constant temperature for a long time. FIG. 5 of the accompanying drawings schematically illustrates a reaction apparatus and a reaction cartridge disclosed in Japanese Patent No. 3558294 as conventional art. The above-cited document discloses a technique of injecting liquid into a cartridge 12 through an injection port formed in the substrate of the cartridge 12 by way of a pump 52.
When injecting liquid into the cartridge 12, firstly the cartridge 12 is fitted to a containing site 58 arranged in the reaction apparatus 50. The, as a result, a closed space is produced to run from the pump 52 to a port 59 arranged in the reaction apparatus by way of the cartridge 12. No gap should be produced between apertures 23, 24 arranged in the cartridge and a flow channel 56. The liquid injected into the liquid injection port 51 arranged in the reaction apparatus 50 moves into the flow channel 56 when the port 59 is exposed to the atmosphere and the pump 52 is operated.
The liquid that has moved into the flow channel 56 then passes through the aperture 23 by way of the pump 52 and is injected into injection port 16 in the inside of the cartridge 12. The liquid that has been injected into the injection port 16 then moves into a reaction chamber 22 by way of a flow channel 20 arranged in the inside of the cartridge 12. The internal temperature of the reaction chamber 22 is held to the level suitable for the reaction by means of a temperature regulator 57. When the substance and/or the waste liquid produced in the reaction chamber 22 needs to be taken out, it can be done so by moving the liquid from the cartridge 12 to the port 59.
The internal pressure in each of the flow channels in the reaction apparatus 50 and the cartridge 12 rises when the pump is operated. If the reaction apparatus 50 and/or the cartridge 12 is clogged and consequently the internal pressure rises or falls extremely there, the rise or the fall, whichever appropriate, is detected by either or both of the two pressure detectors 54 so that the operation of the pump can be stopped.
A particular care needs to be taken when examining genes extracted from a blood specimen or the like since the specimen may be contaminated by some other specimen to give rise to examination errors.
However, when the above-described conventional art is used and liquid is injected into the cartridge by way of the pump, the liquid passes by the inner wall of the pump. In other words, the inner wall of the pump is exposed to any liquid that passes there. Thus, if the inside of the pump is thoroughly washed and cleaned, the problem of contamination by some other specimen can occur.
Additionally, with the conventional art, liquid is driven to move by applying positive pressure to the injection port of the cartridge. Therefore, the apparatus can be damaged and liquid can leak unless the operation of the apparatus is stopped immediately when a trouble such as clogging occurs. Thus, the apparatus has to be provided with a pressure sensor or similar instrument.